There has been known an endoscope configured to analyze color information of an endoscopic image and obtain information (hereinafter, referred to as biological information) regarding condition of a biological tissue which is an object.
In Japanese Patent Publication No. 5302984 (hereinafter, referred to as patent document 1), an endoscope system configured to generate an oxygen saturation image which is imaged information regarding oxygen saturation degree of bloodstream hemoglobin is described. The endoscope system disclosed in patent document 1 is configured to obtain the oxygen saturation degree for each pixel based on relationship between color signals of two frames which are photographed subsequently by alternately using two kinds of illuminating light having different wavelength spectra (i.e., white light and oxygen saturation degree measurement light which is a narrow band), and generate the oxygen saturation degree image represented by a color difference signal related to the oxygen saturation degree (i.e., pseudo-color). Further, the endoscope system disclosed in patent document 1 is further configured to calculate reliability of the oxygen saturation degree for each pixel, and determine saturation of the pseudo-color based on the reliability.